European Patent Application Publication Number 0 475 213 A1 published Mar. 18, 1992 Bulletin 92/12 (hereinafter "EP Application") and U.S. Pat. No. 5,655,282 (hereinafter "U.S. Pat. No. '282") disclose a thermal insulating glazing unit having three or more sheets with a spacer frame between and adhered to adjacent glass sheets. Although the techniques for making insulating glazing units having three or more sheets disclosed in the EP Application and U.S. Pat. No. '282 are acceptable, it would be advantageous to provide a multi-sheet glazed unit that does not have a spacer frame between adjacent glass sheets thereby reducing the number of spacer frames required in the fabrication of such units.
U.S. Pat. No. 5,531,047 (hereinafter "U.S. Pat. No. '047") discloses multi-sheet glazing units having one or more inner glass sheets spaced from and between a pair of outer glass sheets. In general, the outer glass sheets are separated by and secured to a spacer frame having a U-shaped cross section. On the base of the spacer frame between the outer legs is a layer of a pliable material having one or more groove(s) for receiving edge portions of the inner glass sheet(s). The unit of U.S. Pat. No. '047 is fabricated by wrapping spacer stock around the inner sheet(s) while positioning the edge portions of the inner sheet(s) in the groove(s) of the pliable material to position the inner sheet(s) within the spacer frame. After the inner sheet(s) is(are) within the spacer frame, the outer sheets are secured to the outer surfaces of the spacer frame by a moisture-impervious sealant. Although the techniques disclosed in U.S. Pat. No. '047 are acceptable, there are limitations. For example, positioning the spacer stock around the inner sheet(s) may disturb the pliable material on the base of the spacer frame, making the unit unsightly. Further mounting the intermediate sheet(s) in the pliable material on the base of the spacer stock requires time and mounting precision.
U.S. Pat. No. 5,644,894 (hereinafter "U.S. Pat. No. '894") discloses multi-sheet glazing units having one or more inner glass sheet(s) mounted within a U-shaped spacer frame and outer sheets adhered to outer surfaces of the spacer frame by a moisture-impervious sealant. The intermediate sheet(s) is(are) held in position by spaced rows of raised portions formed in the base of the spacer frame. Although the glazing units disclosed in U.S. Pat. No. '894 are acceptable, there are limitations. More particularly, providing spaced rows of raised portions in the base of the spacer frame requires an extra step in the process of making the spacer frame.
U.S. Pat. No. 5,553,440 (hereinafter "U.S. Pat. No. '440") also discloses multi-sheet glazing units having three or more glass sheets. In general, the units include a pair of outer glass sheets separated by and adhered to outer opposed surfaces of a spacer frame having a U-shaped cross-section. A sheet retaining member mounted between the upright legs of the spacer frame has one or more groove(s) for receiving marginal and peripheral edge portions of one or more inner sheet(s). Although the glazing units taught in U.S. Pat. No. '440 are acceptable, there are limitations. More particularly, wrapping the spacer stock around the inner sheet(s) while positioning the edge of the inner sheet(s) in the groove(s) of the sheet retaining members requires assembly time and precision.
United States Statutory Invention Regulation No. H975 (hereinafter "Publication H975"), published Nov. 5, 1991, discloses a multi-sheet unit having a pair of outer sheets spaced from one another by and secured to a spacer frame. An example of Publication H975 discloses the construction of the unit by mounting the edge supports on the edge portions of an inner sheet and setting the inner sheet having the edge supports within the closed spacer frame. Thereafter, the edge supports are secured to the frame. As can be appreciated, mounting edge supports on the edges of an inner sheet and thereafter, securing the edge supports to the spacer frame is time consuming.
As can now be appreciated, it would be advantageous to provide multi-sheet glazing units, i.e., glazing units having three or more sheets, and methods of making same that do not have the limitations of presently available multi-sheet glazing units and methods of making same.